Digital oscilloscope with spectrum analyzer MDO3052. The main scheme for removing the frequency response

Working with the oscilloscope ...

It all starts with measuring probe!

Probe wire is coaxial. The central core of the probe is signal, earth braid (minus or common wire).

On some probes, especially on modern oscilloscopes, a voltage divider (1:10 or 1: 100) is built inside, which allows you to measure a wide range of voltages. Before taking measurements, pay attention to the position of the toggle switch on the dipstick to avoid measurement errors.

The probe has a built-in compensation capacitor. In the low frequency band (below 300Hz), its effect on the gain is absent, but in the 3kHz - 100MHz band, a significant change in gain is evident.

The oscilloscopes have an internal square-wave generator, the signal of which is output to the front panel, to the "calibration" terminal. A calibration signal is provided specifically for adjusting the compensation capacitance. The frequency of this signal is usually 1kHz, with a 1Vp-ppp. The probe is connected to the “calibrate” terminal and is adjusted to obtain the most correct waveform.

We connect the probe to the oscilloscope ...

The oscilloscope input can be closed or open... This allows the signal to be connected to amplifier Y either directly or through a coupling capacitor. If the input is open, then both DC and AC will be fed to amplifier Y. If only the variable is closed.

Example 1. We need to see the ripple level of the power supply. Let's say the voltage of the power supply is 12 volts. The ripple value can be no more than 100 millivolts. Against the background of 12 volts, ripples will be completely invisible. In this case, we use a closed entrance. The capacitor filters out the DC voltage. On amplifierYonly an alternating signal is received. The ripple can now be amplified and analyzed!

Use the knobs to scale the waveform on the screen.Gain and Duration.

The Gain knob scales the signal along the Y-axis. It determines the division value of one cell byvertical lines in volts.

The Duration knob scales the signal along the X-axis. It determines the horizontal division value of one cell in seconds.

Example 2.Based on the values indicated by these knobs and the number of cells occupied by the signal, you can determine the time parameters of the signal in seconds and its amplitude in volts. Based on this data, you can calculate the pulse duration, pause, period and frequency of the signal.

In the case when the oscillogram does not fit on the screen and it is necessary to move it vertically or horizontally, usehandles for vertical and horizontal movement.

For convenient display of cyclically repeating signals, usesynchronization... Synchronization draws individual pulses, always starting from the same point on the screen, thereby creating the effect of a still image.

Sweep mode defines the behavior of the oscilloscope. There are three modes: AUTO, Normal, and Single.

Auto modeallows you to capture images of the input signal even when the trigger conditions are not met. The oscilloscope waits for the trigger conditions to be met for a certain period of time and, if the required trigger signal is absent, it automatically starts recording.

Waiting modeAllows the oscilloscope to record waveforms only when the trigger conditions are met. If these conditions are not met, the oscilloscope waits for them to appear, the previous oscillogram is saved on the screen, if it was registered.

V single sign-on modeafter pressing the RUN / STOP key, the oscilloscope will wait for the trigger conditions to be met. When they are executed, the oscilloscope will make a single acquisition and stop.

Launch systemTrigger, determines when the oscilloscope starts recording data and displaying the waveform. If the trigger system is set up correctly, the screen will display clear waveforms.

The oscilloscope supportsa number of types of launching sweep: Edge Trigger, Slice Trigger, Arbitrary Edge Trigger.

Runlevel- This is the voltage value, upon reaching which the oscilloscope begins to draw the oscillogram.

Spectrum Analyzer Operation ...

There is a general technique for studying signals, which is based on the decomposition of signals intoFourier seriesusing the algorithm for fast computation of the discrete Fourier transform,Fast fourier transform (FFT).

This technique is based on the fact that you can always pick up a number of signals with such amplitudes, frequencies and initial phases, the algebraic sum of which at any time is equal to the value of the signal under study.

This made it possible to analyze the signal spectrum in real time.

Let's consider the principle of operation of a typicalFFT analyzer.

The signal under investigation arrives at its input. The analyzer selects consecutive intervals ("windows") from the signal, in which the spectrum will be calculated, and performs an FFT in each window to obtain the amplitude spectrum.

The calculated spectrum is displayed as a graph of the amplitude versus frequency.

Parameter FFT Length, the length of the window - the number of analyzed signal samples - is of decisive importance for the type of spectrum. The larger the FFT Length, the denser the frequency grid over which the FFT decomposes the signal, and the more frequency detail is seen in the spectrum.

To achieve a higher frequency resolution, it is necessary to analyze longer sections of the signal.

When it is necessary to analyze fast changes in the signal, the window length is chosen to be small. In this case, the analysis resolution increases in time and decreases in frequency. Thus, the frequency resolution of the analysis is inversely proportional to the time resolution.

One of the simplest signals is sinusoidal. What will its spectrum look like on an FFT analyzer? It turns out that it depends on its frequency. FFT decomposes the signal not into those frequencies that are actually present in the signal, but along a fixed uniform frequency grid.

If the tone frequency matches one of the FFT grid frequencies, then the spectrum will appear "perfect": a single sharp peak will indicate the tone frequency and amplitude.

If the tone frequency does not coincide with any of the frequencies of the FFT grid, then the FFT will "collect" the tone from the frequencies available in the grid, combined with different weights. In this case, the spectrum graph is blurred in frequency. This blurring is usually undesirable as it can mask weaker signals at adjacent frequencies.

To reduce the blurring effect, the signal is multiplied byweight windows- smooth functions falling to the edges of the interval.

They reduce spectrum blur at the expense of some degradation in frequency resolution.

The simplest window is rectangular: this is a constant 1 that does not change the signal. It is equivalent to the absence of a weighting window.

One of the popular windows ishamming window... It reduces the smear level by about 40 dB from the main peak.

Weight windows differ in two main parameters: the degree of broadening of the main peak and the degree of suppression of spectrum smearing ("side lobes"). The more we want to suppress the sidelobes, the wider the main peak will be. The rectangular window blurs the top of the peak least of all, but has the highest side lobes.

Kaiser windowhas a parameter that allows you to select the desired degree of sidelobe suppression.

Another popular choice isKhan's window... It suppresses the maximum lateral lobe weaker thanhamming window, but on the other hand, the other side lobes fall off faster with distance from the main peak.

Blackman windowhas stronger sidelobe suppression thanKhan's window.

For most tasks, it is not very important which type of weight window to use, the main thing is that it be there. Popular choice -Khan or Blackman... The use of a weighting window reduces the dependence of the spectrum shape on a specific signal frequency and on its coincidence with the FFT frequency grid.

Longer FFT windows can be used to compensate for peak broadening when using weight windows: for example, not 4096, but 8192 samples. This will improve the resolution of the analysis in frequency but degrade in time.

Working with the signal generator ...

When it comes to measuring technology, the first thing that comes to mind is usually an oscilloscope or logic analyzer (recording devices).

However, these instruments are only capable of making measurements if they receive a signal.

Many examples can be cited when such a signal is absent, while on the investigatedthe device will not receive an external signal.

Example.It is necessary to measure the characteristics of the developed circuit and make sure that it meets the requirements.

Therefore, a set of instruments for measuring the characteristics of electronic circuits should includestimulating signal sources and recording devices.

Signal generatorrepresentssource of the influencing signal.

Depending on the configuration, the generator can generate analog signals, digital sequences, modulated signals, intentional distortion, noise, and much more.

The generator can create “ideal” signals or add to the signal the specified distortions or errors of the desired magnitude and type.

Signals can take many different forms:

sinusoidal signals;
meanders and rectangular signals;
triangular and sawtooth signals;
drops and impulse signals;
complex signals.

Complex signals include:

signals with analog, digital, pulse-width and quadrature modulation;
digital sequences and coded digital signals;
pseudo-random streams of bits and words.

One of the varieties of generators isoscillating frequency generator.This is a special kind of signal generator in which the output signal frequency changes smoothly in a certain interval, and then quickly returns to the initial value. During this time, the amplitude of the output signal remains constant.

If a radio amateur has an oscilloscope at his disposal, then using it in conjunction with a sweeping frequency generator, you can easily check and adjust quartz, electromechanical and LC filters, radio frequency and IF paths of a receiver or transmitter, investigate the frequency response of radio and television equipment in a wide frequency range.

The results of the comparison of technical characteristics and the internal structure of the measuring complex will be described in detail in the next video.

Hello. I offer an overview of the designer for self-assembly of an entry-level DSO062 oscilloscope-frequency meter with an FFT (Fast Fourier Transform) algorithm.
The Fast Fourier Transform (FFT) is a mathematical function that allows you to obtain from the time dependence of a signal its frequency components, i.e. carry out spectral analysis of signals.
The constructor is quite simple, so it can be recommended to the most novice radio amateurs.
In the review I will try to describe in detail all the stages of the assembly and illustrate them with photographs.
Eh, if I got such a constructor in childhood, when I went to the radio shop, I would be happy ...

First, let's take a look at Wikipedia:

An oscillograph (Latin oscillo - swinging + Greek γραφω - writing) is a device designed to study (observe, record, measure) the amplitude and time parameters of an electrical signal supplied to its input, either directly on the screen or recorded on a photographic tape.

Oscilloscopes were originally mechanical, then electron-beam, and now they are digital.
An oscilloscope is for a radio amateur, it's like a tester for an electrician, it's like binoculars for a military man, it's like a microscope for a biologist ... This chain can be continued indefinitely. Therefore, it's time to move on to the review.

Specifications:

The characteristics, of course, are very modest, indicating that this device cannot be a measuring instrument, but only a demonstration device for acquaintance and getting initial skills. However, this device boasts a frequency counter and spectrum analyzer function. You can also note the ability to save "screenshots" in memory with the ability to transfer them to a computer.

Packing and equipment:

The most budgetary packaging is a plastic bag.

As you can see from the photo, most of the elements are already mounted on the printed circuit board, it remains to solder: 1 diode, 6 capacitors, 1 inductance, 1 stabilizer, 2 connectors, 9 buttons, 1 LCD indicator. Also included is a radiator, stands, screws and cable.
The set includes 3 pieces of fiberglass, 2 of which are the front and rear panels, but the middle one is a printed circuit board with elements:

As I wrote above, SMD elements (surface mount elements) are already mounted on the printed circuit board. The printed circuit board has a green protective lacquer mask (the so-called "green") and silk-screen printing. The board is badly cleaned, tk. if you look closely, you can see small "balls" of solder:

The set includes one more printed circuit board as part of the LCD indicator:

First, you need to "download" the archive with documentation and installation instructions. All documents are in English.
Let's consider the device block by block.

+5 volt stabilizer:

The converter is assembled on a 7805 linear voltage regulator microcircuit. According to the passport, up to 30 volts can be supplied to the input of this stabilizer, but this cannot be done, because the circuit uses not only the output voltage of +5 Volts, but also the input VRAV + from which a negative voltage is later made to power the operational amplifiers. At the output of the stabilizer there is a jumper JP1 that is open from the factory, which will need to be closed after all the necessary elements are soldered and the output voltage will be 5 Volts. Those. this is such a "protection from the fool."

Bipolar power supply:

To power the operational amplifiers installed in the analog input part, a bipolar power supply is required, i.e. "+" and "-" relative to power supply zero. An input voltage of +9 Volts is used as a source of positive polarity, which is filtered from interference by inductance L3 and capacitor C18.
To obtain a negative voltage, the self-inductance EMF of inductance L2 is used, which is rectified by diode D7 and smoothed by filter C14-L1-C15.

Analog input part:

The analog input part is based on operational amplifiers and. This part also contains switches for selecting the input range.

Analog-to-digital converter (ADC):

The signal from the output of the analog part is fed to an 8-bit parallel ADC TLC5510. With this ADC, the analog signal is converted into digital with a resolution of 8 bits, i.e. 256 values

Microcontroller:

The "brain" of this oscilloscope is the AVR microcontroller, which receives the digital value of the input signal, performs the necessary mathematical transformations and outputs the data to the LCD screen. In parallel with its main task, this microcontroller outputs a 500 Hz test signal, as well as VGEN pulses for a negative polarity source.

LCD display:

An LCD display is used to display the image, which is a monochrome 128x64 dot matrix. Microcontroller interface - 8-bit parallel. The variable resistor POT1 adjusts the image contrast.

Assembly:

Having familiarized yourself with the main nodes, it's time to move on to the assembly.
To begin with, it is proposed to check the polarity of the soldered diodes D7 and D1:

We check:

The diodes are soldered correctly.

Step 1: Install diode D3

There is only 1 diode in the kit, it is difficult to confuse. The gray bar is the "cathode", i.e. "-". Install and solder as shown on the board.

Step 2: Installing Electrolytic Capacitors

There are 6 capacitors in a set: 1 for 470 uF (more) and 5 for 100 uF (less). It is also difficult to confuse. The capacitors have a negative contact "-" marked on the case. We solder as indicated on the board.

Step 3: setting inductance L2

There is only one inductance, it has no polarity, so we solder it as it goes.

Step 4: Install J4 Connector

This 2-row 10-pin connector is used for programming the microcontroller, which is already programmed, so if you do not intend to reprogram it, then the connector is not required to be soldered.

Steps 5 & 6: Install J5 & J6 (or J1)

J5 is the power connector. J6 (or J1, whichever comes with) is the signal input connector. Soldered into place. Due to the fact that the connectors have thick leads, you need to solder carefully so as not to overheat their cases.

Step 7: Install the J8 test signal terminal

Here it is proposed to make a loop from the bitten off output of a diode or capacitor and solder in this way (later it will be necessary to connect to this loop with an input "crocodile" to check the operability):

Step 8: Install the gimbal with heatsink

First, you need to shape the leads of the 7805 stabilizer chip, screw it to the radiator and the case, and only then solder.

Step 9: Check the 5 Volt supply voltage

Now you need to apply 9-12 volts DC to the power connector, according to the polarity and measure the voltage at the TP5 test point. The voltage should correspond to 5 volts.

If everything is in order, then you can proceed to the next step, and if not, then it is necessary to recheck the installation of the elements (diode, stabilizer).

Step 10: Install jumper JP1.

Jumper JP1 is foolproof. This was done in order not to "burn" all the other elements in case of improper installation. But since we have reached this step, then everything is mounted correctly and the jumper can be installed. It is also done from trimming the output.

Because then the buttons and switches should be soldered, then first I recommend washing the board from the flux. Later, this will need to be done much more carefully so as not to wet the controls. You can wash it off with alcohol or an alcohol-gasoline mixture. I wash with isopropyl alcohol.

Steps 11 & 12: Installing Buttons and Switches

It is recommended in the manual to solder the buttons only diagonally at first, i.e. not 4 but 2 legs in each, then try on the front panel and adjust the depth of the buttons so that they are well pressed. In reality, it turned out that due to the excessive length of the buttons, having seated them as deep as possible, I still had to put washers under the struts in order to slightly raise the front panel. Those. we solder all the buttons as close to the board as possible.

Step 13: Installing the LCD indicator

First, you need to solder a single-row 20-pin ruler to the LCD indicator board. But you need not to confuse and solder where the holes are signed. On the other hand, solder 2 two-pin pieces:

You need to solder so that the pins are perpendicular to the board. After that, try to put the LCD board on the main one and make sure that the leads of the soldered elements do not reach the display board. If everything is in order, solder the reverse sides of the pins from the side of the main board.

And now is the time to remove the remaining flux, but more carefully. For this I use cotton swabs dipped in isopropyl alcohol.

First start-up:

The oscilloscope is soldered, washed from the remains of the flux, a thorough examination of all contacts was made for "non-drip" or "snot", and if everything is in order, turn on the power:

The screen lit up and even shows something. In fact, at first I did not have any image. The screen glowed green and that's it. But after adjusting the contrast with the variable resistor POT1, everything fell into place.
The next stage is assembly and testing.

Assembly:

There is nothing complicated in the assembly. The set contains 8 stands (4 short and 4 long). The corners of all boards are provided with holes for stands. Short ones are installed on the side of the LCD screen and buttons, i.e. from the front, and long from the back.

The front and rear panels are fixed to the stands with 8 screws, which are also included in the kit. Before installing the front panel, you must put on the caps on the buttons. In order for the buttons to be pressed properly, I had to put one washer between each rack and the front panel. Here's what happened:

Nutrition:

As a power source, the manufacturer suggests using any source with a voltage of up to 12 volts DC or AC. The fact is that there is a diode at the input that protects the device from polarity reversal, and also plays the role of a half-wave rectifier. The current consumption is stated as "<200 мА". Проверим:

Yes, the current consumption was 113 mA. Due to the fact that a linear voltage regulator is used, the current will not change significantly when the supply voltage changes. Those. that at 9 volts, that at 12 the current is almost the same. Only in the second case the stabilizer radiator heats up more.
To connect the power, you need to separately purchase the following connector:

It costs 15 rubles.
Or use a power supply with the required connector ("+" must be inside, "-" outside). I ended up with the following source:

Governing bodies:

Let's "go over" the governing bodies. There are 3 switches and 9 buttons. Let's start with the switches:
AC / DC / Freq- input type switch. "AC" - measurement of alternating current, there is a "cut-off" of the DC component. "DC" - measurement of direct current taking into account the constant component of the signal. "Freq" - frequency measurement mode (frequency meter).
GND / 1V / 0.1V and "X5 / x2 / x1"- these 2 switches adjust the sensitivity, i.e. the value along the "Y" axis. The first switch selects the base value, and the second the multiplier. The result is obtained by multiplying the selected values. For example, the first switch is set to "0.1V", and the second to "x2", the result in this case will be: 0.2 volts per cell.
Now the buttons:
SEC / DIV- Changing the "sweep frequency", i.e. time along the "X" axis. When you press the button, the corresponding icon on the screen is highlighted and then you can change the value of the "time per cell" using the buttons [+] and [-] .
V.POS- Choice of changing the vertical position. When you press the button, the corresponding icon on the screen is highlighted and then you can make a vertical shift with the buttons [+] and [-] .
H.POS- Choice of changing the horizontal position. When you press the button, the corresponding icon on the screen is highlighted and then you can make a vertical shift with the buttons [+] and [-] .
MODE- Selection of the synchronization mode. When you press the button, the corresponding icon on the screen is highlighted and then you can change the synchronization mode with the buttons [+] and [-] .
SLOPE- Change the polarity of synchronization. When you press the button, the corresponding icon on the screen is highlighted and then you can change the polarity of the synchronization using the buttons [+] and [-] .
LEVEL- Choice of the level of synchronization. When you press the button, the corresponding icon on the screen is highlighted and then you can change the synchronization level with the buttons [+] and [-] ... Subsequent clicks on LEVEL selects "internal" or "external" synchronization and enables or disables the synchronization output.
OK- "Freeze" the screen. Those. when the button is pressed, the inscription "HOLD" appears and the image stops changing. Pressing it again returns to normal mode.

Testing:

First, let's connect the oscilloscope input to the test signal output J8. There should be a square wave with a frequency of 500 Hz and an amplitude of 5 volts. We look:

The modes "1 volt per cell" and "0.5 ms per cell" are selected. The amplitude is about 5 cells, i.e. 5 volts, period 4 cells, i.e. 2 msec. We translate the period into frequency f = 1 / T = 1 / 0.002 = 500 Hz. That's all right. In parallel, I connected a multimeter in frequency measurement mode. The readings also matched.
Go ahead, I do not have a signal generator, so we will make do with improvised means. Let's see the frequency and waveform from the output of a conventional network transformer:

Sinusoid with a frequency of 50 Hz.
Next, I assembled the simplest generator on a timer microcircuit.

Connect the oscilloscope under study and the ISDS205C to the output of the resulting generator.

Next, let's experiment with the signal shape, for which we connect an R-C chain 2kOhm-5nF to the output:

Let's increase the capacitance to 1 μF, but also lower the frequency:

The waveforms are similar, and the frequencies are similar.

FFT mode:

FFT or in English FFT is. Without going into details, this function allows the user to use the oscilloscope to analyze the signal not only in the time domain, but also in the frequency domain. This algorithm is especially useful when spectrum analysis is required, but specialized instruments such as spectrum analyzers are not available. At the same time, one must clearly understand that an oscilloscope is, first of all, an oscilloscope, and not a means of measuring the frequency spectrum, although it has such an opportunity. Therefore, the metrological characteristics of oscilloscopes in the FFT mode are not standardized.
The oscilloscope switches to FFT mode and vice versa by long pressing (3 seconds) on the button MODE... Button HPOS you can select the number of points for the FFT: 256 or 512. Use the buttons [+] [-] you can change the sampling rate.
To test this mode, connect the oscilloscope input to the output of the internal test generator:

The generator frequency is 500 Hz, you can see the maximum signal level exactly at this frequency, and then observe the damped harmonics at frequencies of 1500 Hz, 2500 Hz, 3500 Hz, etc.

To save a screenshot:

You can take a screenshot and save it either to the internal non-volatile memory (up to 6 pictures), or transfer it as a BMP file to a computer. This can be done as follows:

Internal storage:
1) "Freeze" the screen with the button (HOLD state).
2) Press and using [+] or [-] select 1 of 6 memory locations.
3) Press to record the frozen screen to the selected cell.

Viewing Saved Screens:
1) Enter HOLD mode by pressing the button.
2) Press and using [+] or [-] select 1 of 6 memory locations.
3) Press to display the image from the selected cell.

Transfer the screenshot to your computer.
First, you need to connect the oscilloscope to your computer via a serial port. For this I used a USB-COM converter with TTL levels by connecting it to the J5 connector:
Next, you need to run a program on your computer that supports receiving data using the protocol Xmodem... On WinXP, this is HyperTerminal. On Win7 and older, HyperTerminal is not. How to use - I find it difficult to answer. I was lucky to have an old WinXP laptop in stock. When receiving data, you must select the following port parameters: 38400bps, 8 data bits, 1 stop bit, no parity, no flow control.
Select the file name with the BMP extension and click "waiting for reception".
At this time, switch the oscilloscope to the HOLD state with the button, press and then. At this time, the file transfer should begin. That's what I did:

Outcomes:

Well, it's time to finish and summarize.

Ease of assembly, available even to the most novice radio amateurs;
+ "3 in 1" device: oscilloscope, frequency meter, spectrum analyzer;
+ Ability to save "screenshots" in memory and on a computer;
+ Workmanship;
+ Detailed description of the assembly process and troubleshooting.

Low resolution LCD display and its monochrome;
- Modest characteristics (the sampling frequency is only 2 MHz, in order to examine the waveform you need at least 10 points per period, therefore the maximum frequency of the input signal is in the region of 200 kHz).

As I wrote at the beginning of the review: "Oh, if I got such a constructor in my childhood, when I went to the radio shop, I would be happy ...", and this is true. The constructor is very good for getting basic skills in working with an oscilloscope, frequency counter, spectrum analyzer. Using this device, you can adjust the simplest electronic circuits, despite the fact that this is a toy to a greater extent than a measuring device. Why did I order it? Yes, it just became interesting. I decided to show and tell what it is and "how it is eaten."
I hope the review will be helpful. If I see that such reviews are of interest to readers, I will continue to order different constructors.

Good luck!!!

The product is provided for writing a review by the store. The review is published in accordance with clause 18 of the Site Rules.

I plan to buy +51 Add to favourites I liked the review +73 +123

Miniature model of 2-channel USB digital storage oscilloscope. Made in the form of a prefix to a PC. Connects via USB port. The original design and excellent technical characteristics invariably attract the attention of specialists.

2 independent channels with bandwidth up to 100 MHz
write buffer up to 128 kB per channel (user-defined)
freely selectable pre-record / post-record length
high sensitivity (from 10 mV / div)
automatic tuning to input signals
advanced sync modes
large selection of cursor and automatic measurements
statistical measurements and plotting of histograms
spectrum analyzer (FFT)
digital phosphor
alarm
connection to PC via USB 2.0
in / out external synchronization (compatibility - TTL)

USB Oscilloscope Specifications

10 GHz sampling rate (stroboscopic mode)
sampling rate 100 MHz (real time)
vertical deviation coefficient 10 mV / div ... 10 V / div with a step of 1-2-5
8 bit resolution
frequency range -3 dB: 0 Hz ... 100 MHz (DC), 1.2 Hz ... 100 MHz (AC)
input impedance 1 MΩ or 50 Ω
maximum input voltage: ± 50 V at Rin = 1 MΩ, ± 2.25 V at Rin = 50 Ohm
minimum sync pulse repetition period 20 ns
minimum sync pulse duration 10 ns
parameters of the input signal to ensure extended synchronization at the inputs "CH1", "CH2" (in relation to a rectangular pulse): amplitude - not less
20 mV, duration - not less than 50 ns, repetition period - not less than 50 ns
range of values of the sweep factor 10 ns / div .... 0.1 s / div
calibrator 1 kHz, 3 V pk-pk
+5 V power supply
weight 0.19kg
overall dimensions 150x85x32 mm

AKTAKOM Oscilloscope Pro software (supplied with the device):

PURPOSE:

The application is designed to fully control USB oscilloscopes ACK-3106, ACK-3116, ASK-3002, ASK-3102 and ASK-3202, collect measurement data from two channels, process them, display and save them on a computer.

POSSIBILITIES:

The application provides detection and compilation of a list of available virtual devices connected to the computer locally (via the USB interface) or via the Ethernet / Internet network; initialization and testing of the selected USB oscilloscope instance.

The application provides control of all parameters available for configuring this type of equipment (see the description of supported devices) and reading data in a frame-by-frame (oscilloscope mode) or continuous (recorder mode) method. Collected oscillograms are displayed on the main and overview graphs, graphs can be scaled by the user arbitrarily, the graph drawing style is customizable (points, segments, splines), persistence and digital phosphor modes are available for display. For manual measurements on a graph, two cursors and ten custom marks are available, positions and intervals for cursors and marks are displayed numerically in a separate program window.

Both the digital oscilloscope mode with sequential acquisition of waveforms of limited length and the recorder mode with continuous acquisition and display of data for an unlimited time are supported.

The application allows you to record waveform data into files in the form of numerical data (universal bit format AKTAKOM USB Lab). The numerical data files can then be reloaded into the application for viewing and analysis.

Using the utility, you can convert a data file for reading by other AKTAKOM USB Lab applications in the same AKTAKOM USB Lab format, or convert the data into CSV text format, which can then be opened by any text editor or spreadsheet processor. It is possible to save to a file a ready-made image of the received signals on the graph in a file in BMP format or in vector formats WMF or EMF.

Measurement data printing is also supported, printing can be directed to a printer or to a graphic file.
An analysis module is built into the application for processing and automatic measurements.

THE STANDARD FUNCTIONS OF THE USB Oscillographic Analysis Module Includes:

digital filtering (polynomial, cumulative and spectral filters);
digital signal transformations (amplification / attenuation of the amplitude, compression / expansion of the time scale, vertical reflection, horizontal reverse, noise addition);
various mathematical functions of signals by channels (sum, difference, product, ratio, root mean square of channels, derivative, channel integral, channel product integral, channel correlation);
alarm that monitors the signal going beyond the set amplitude limits (available both in the recorder mode and in the oscilloscope mode);
functions of voltmeter, frequency meter, phase shift meter and integrator;
automatic measurement of pulse parameters (amplitude, peak-to-peak, overshoot, median, mean, standard deviation, frequency, period, pulse duration, duty cycle, rise time, fall time);
spectral analysis (selectable section of the oscillogram, determination of SOI, fundamental harmonic parameters, cursor measurements on the spectrogram, windows are supported: rectangular, triangular, Hann, Heming, Blackman, Blackman-Harris, Gauss, conic cosine, flat, exponential) and signal synthesis;
statistical processing of measurement results (for the selected parameter, the average, minimum, maximum, standard deviation are determined, a histogram of the probability distribution is built, the asymmetry and kurtosis of the distribution are determined, cursor measurements are made using the histogram);
formula calculator;
editor for emulating signals.

The application allows the user to manually adjust the colors of the graph elements and the line width of the oscillograms or load these settings from the previously saved files of color schemes. The size, position and transparency of all windows in the application can also be customized by the user. All program settings can be written to a configuration file and then loaded.

Advanced sync modes

	Front launch	Crossing a given voltage level in a given direction
	Transition trigger	By rise or fall time
	Duration trigger	By pulse duration
	Pause start	No impulse for the specified time
	Glitch launch	Pulse duration less than sampling period
	Run on welt	By pulse amplitude
	Window launch	By signal output / input to the threshold window
	Boolean triggering	Logical function of channels
	Logical start	Logic function of channels linked to sync pulses
	Sequential start	Event B after event A (according to a specified delay and / or number of events)

The minimum value of the duration of the measured interval: not less than five sampling periods with a repetition interval also, not less than five sampling periods.
The maximum value of the duration of the measured interval: no more than 65535 sampling periods.
With sequential types of triggering, the sources of events A and B can be channels A, B, external input. The conditions for triggering sequential types are the edges of the signals of events A, B. The number of repetitions of events A, B: from 1 to 255.

Possibilities

The extended trigger sync option allows the instrument to be used as a smart sync device. At the output of the X1 connector, according to the specified conditions, it is possible to receive a TTL level trigger signal for any other device by an external signal or signals (via the "CH 1" and / or "CH 2" inputs).

Standard complete set

USB oscilloscope
manual
Software
- AOP Aktakom Oscilloscope Pro Virtual Oscilloscope Software
- AUNLibUSB 1.2.6.0 Driver for Virtual USB Lab Devices

The software in the standard delivery does not have physical media and can be downloaded on the website in the "" section after purchasing and registering the device, indicating its serial number.

To download the software, click the Download button or go to the section

Spectral Signal Analysis Using LeCroy Oscilloscopes and Dedicated Spectrum Analyzer Mode

Introduction

An oscilloscope is a device that provides a visual display of the input signal in the time domain, that is, it displays the value of the signal amplitude along the time axis. But for a wide class of signals, a clearer idea of the nature of the processes occurring gives not a temporal, but a spectral representation of the signal, when the amplitudes of the harmonic components of the signal are displayed along the horizontal axis. These signals include the frequency response of amplifiers, phase noise of generators, mechanical vibrations, transients, etc., which are easier to observe in the frequency domain. All modern digital oscilloscopes have the ability to mathematically process the received data using the Fast Fourier Transform (FFT) algorithm to convert the input signal into its spectral display. The FFT principle is discussed in some detail in.

However, the display of the signal spectrum using the FFT has a number of disadvantages, which somewhat complicate the spectral analysis. To display the spectrum correctly, the user needs to:

Determine what maximum frequency component he wants to see in the spectrum.
According to the Kotelnikov theorem, fix the sampling frequency of the oscilloscope at twice the maximum frequency component of the spectrum (or at least the closest upper value).
By changing the value of the sweep factor in the direction of increasing, set the maximum possible value of the oscilloscope memory length, since the frequency resolution is proportional to the used memory length of the digital oscilloscope.
Select one of the windows, depending on the problem being solved - frequency measurement or amplitude measurement.
Using the stretching mode, select the required part of the spectrum and take measurements.

This sequence of actions is quite long and requires certain skills. When moving on to analyze other frequency components, a new parameter setting is required. In addition, not all digital oscilloscopes are capable of fully setting the parameters listed above. Quite simple digital oscilloscopes (Tektronix TDS-1000, TDS-2000, TDS-3000 series; LeCroy WaveAce series; GW Instek; Agilent 3000, 5000, 6000 series, etc.) do not have the ability to directly control the sampling rate or memory length ... For these oscilloscopes, the memory is fixed, and the sampling rate is changed by changing the sweep factor. Therefore, the control of the settings of the spectrum display parameters is carried out by measuring the sweep time, which is rather inconvenient when examining the spectrum and does not provide either an accurate setting of the center frequency or frequency resolution. So the spectrum of the FM signal obtained on a Tektronix oscilloscope is shown in Figure 1. As you can see, the oscilloscope displays well one frequency component located near the carrier frequency, but the spectral components are no longer able to display.

Other, more advanced oscilloscopes (for example Tektronix DPO4000 or LeCroy WaveJet and WaveSurfer) have the ability to change the memory length and, as a result, the ability to control the sampling rate. But the FFT principle, for an accurate display of the spectrum, implies initially setting the sampling frequency and only then changing the memory length. For such oscilloscopes, the spectrum display accuracy is much higher and the control is somewhat more convenient than for the above oscilloscopes, but it is still not very easy to achieve a reliable display of the required frequency components. So the FM signal spectrum obtained on a Tektronix DPO4000 oscilloscope is shown in Figure 2. Compared to Figure 1, the FM signal spectrum in Figure 2 looks more realistic, but a detailed study of the frequency components (shown in Figure 2 at the bottom of the screen) is still not very convenient.

Oscilloscopes built on the principle of an open platform fully ensure the correct implementation of the FFT algorithm, good spectrum detail and high frequency resolution. But due to the need to process large amounts of memory (tens of millions of points), the construction of one spectrogram, depending on the power of the control computer and the length of the internal memory, can take up to a minute. So Figure 3 shows an example of displaying the spectrum of an FM signal, similar to Figure 2, but obtained on a LeCroy oscilloscope with an open platform.

With classic spectrum display control like a standard spectrum analyzer does, digital oscilloscopes with FFT mode can't compete.
Classic spectrum analyzer control implies:

Center frequency setting;
Setting the swath;
Bandwidth setting;
Setting the reference level;
Selecting the scale of the vertical scale.

Instead of setting the center frequency and span, any standard spectrum analyzer has the ability to set the start and stop frequencies.

All these shortcomings of spectrum analysis control in LeCroy digital oscilloscopes have been eliminated with the introduction of the Zi-Spectrum Spectrum Analyzer option into the oscilloscopes. When the spectrum analyzer mode is activated, the control menu opens, shown in Figure 4.

The spectrum analyzer settings are controlled by groups of controls, arranged according to their functional purpose - frequency and span; bandwidth; amplitude; modes and measurements.

Setting the center frequency, start frequency, stop frequency, span and bandwidth

The center frequency is set by directly entering the frequency value. The choice of the swath is also carried out by direct dialing. It is also possible to enter the start and end frequencies of the survey. As noted earlier, in order to display the spectrum correctly, first of all, it is necessary to determine the sampling frequency and then, depending on the frequency resolution of the spectrum analyzer, set the oscilloscope memory length. The spectrum analyzer option performs these procedures automatically, eliminating the need to deal with calculations - the user only sets the frequency range, and the oscilloscope calculates and sets the required oscilloscope sampling rate and optimal memory length. The oscilloscope memory length is selected to provide the specified frequency resolution and ensure the maximum screen refresh rate. Convenient and simple. Obviously, the user can set any desired center frequency and span, but the oscilloscope cannot select any sample rate and any memory length, but only a number of available values. Using only the available sample rate and memory values would result in the start and stop frequencies of the spectrum analyzer not matching those specified by the user. To eliminate this paradox, LeCroy oscilloscope, based on the available sampling rate and memory length, automatically scales the displayed part of the spectrum, at which the "extra" part is cut out from the calculated spectrum and only the one that was defined by the user is displayed. The spectrum "surpluses" on the left and right, although stored in the oscilloscope's memory, are not displayed on the screen.

The bandwidth of the spectrum analyzer (Resolution Bandwidth), which determines the frequency resolution, by default, like standard spectrum analyzers, is in automatic mode. As the bandwidth increases, the bandwidth increases, resulting in shorter oscilloscope memory and faster screen refresh rates. When analyzing the spectrum more closely and using a narrower bandwidth, the oscilloscope requires longer memory and longer tracing time. Similar phenomena are fully inherent in stationary spectrum analyzers, but instead of the concept of "screen refresh rate" they operate with the concept of "sweep time", which is, in principle, the same thing. So figure 5 shows an example of reducing the span of an FM signal, the full spectrum of which is shown in Fig. 4., in order to determine the frequency of the modulating oscillation. If to display the full spectral image in Fig. 4, the memory length of 2.5M was enough, which provided a 500 kHz span and a bandwidth of 357.6 Hz, then for a 10 kHz span and a bandwidth of 40.6 Hz, providing observation of a 1 kHz baseband frequency, the oscilloscope is already using the memory length 32M. If necessary, the user can refuse automatic bandwidth selection and set it manually.

Setting the amplitude parameters.

The spectrum amplitude parameters are controlled by changing two parameters:

The scale of the logarithmic scale. The scale can be selected from a range of 1-2-5 ranging from 100 mdB to 100 dB.
The offset of the reference level is carried out in the range from -200 dB to +200 dB.

The entry of values is carried out, as for all parameters of LeCroy oscilloscopes, by direct dialing or by changing smoothly-roughly in the direction of increasing or decreasing.

Spectrum measurements

The traditional FFT used in digital oscilloscopes is mostly hand-controlled marker measurements. The use of automatic measurements, which have very wide capabilities, is difficult to apply specifically for the FFT, since a set of special measurement modes is required to measure the spectrum parameters - searching for peak values in the span, measuring the amplitude and frequency of peaks, setting the center frequency value by the value of the marker frequency, etc. Unfortunately, a standard digital oscilloscope does not have this set of measurements.

In LeCroy oscilloscopes in the "Spectrum" mode, this drawback has been largely eliminated. So figure 6 shows an example of displaying the spectrum of a rectangular signal and an included measurement table.

The principle of measurements in the "Spectrum Analyzer" mode is based on the WaveScan algorithm, which has perfectly proven itself over the past several years, to search for signal sections according to specified parameters. In the measurement mode, the spectrum analyzer searches for peaks in the spectrum, starting with the maximum and measures the frequency and amplitude of the found peaks. The peak with the highest amplitude is assigned the number "1", the second-highest level is assigned the number "2", and so on. The user can set the number of peak searches from 1 to 100. The LeCroy oscilloscope then generates a measurement table, which displays the peak numbers, frequency and amplitude values. On the spectrogram itself, the peaks have a frequency label. Measurements are made in real time, and if in the process of observing the spectrum there is a change in the frequency of harmonics or their amplitudes, the data in the measurement table is updated instantly.

Also, the Spectrum Analyzer has one marker designed to overwrite the center frequency according to the set value of this marker.

In Spectrum Analyzer mode, all other digital oscilloscope measurements are unavailable, but all cursor measurement functions can be used for manual amplitude-frequency measurements.

Math functions with spectrograms

Typically, the signal spectrum, especially with a wide span, has a fairly strong noise track and this is clearly seen in Figure 6. These noises can suppress some of the useful signal required by the user. To eliminate the influence of noise and other random factors in the Spectrum Analyzer mode, LeCroy oscilloscopes have two math functions:

Averaging;
Accumulation of maximum values.

The math function averaging has the same algorithm as the standard waveform averaging function in any digital oscilloscope. The result of averaging the spectrograms is shown in Figure 7, where it is clearly seen that the noise track is significantly reduced.

The algorithm of accumulation of maximum values allows registering only the maximum values for the entire time of accumulation of information. This allows you to reliably display the spectrum of unstable but repetitive signals.

Output:

A specialized spectrum analyzer option used in LeCroy's WaveRunner "A", WavePro 7 Zi and WaveMester 8 Zi oscilloscopes greatly simplifies spectral analysis and gives the user measurement capabilities not available compared to the standard FFT function.
Currently, similar measurement modes are not available from other digital oscilloscope manufacturers.

Literature:

Spectral analysis (.htm class = l> .htm).
Find anomalies and analyze signals in LeCroy oscilloscopes using the WaveScan function (.htm class = l> .htm).

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2 independent channels with bandwidth up to 100 MHz
write buffer up to 128kB per channel (user-defined)
freely selectable pre-record / post-record length
high sensitivity
automatic tuning to input signals
large selection of cursor and automatic measurements
statistical measurements and plotting of histograms
spectrum analyzer (FFT)
digital phosphor
alarm
connection to PC via USB 2.0
in / out external synchronization (compatible - TTL)

Specifications

sampling rate 100 MHz
vertical deviation coefficient 10 mV / div ... 5 V / div with a step of 1-2-5
8 bit resolution
frequency range at the level of –3 dB: 0 Hz ... 100 MHz (DC), 1.2 Hz ... 100 MHz (AC)
input impedance 1 MΩ
maximum input voltage: ± 50 V at Rin = 1 MΩ, ± 2.25 V at Rin = 50 Ohm
minimum sync pulse repetition period 20 ns
minimum sync pulse duration 10 ns
range of values of the sweep factor 10 ns / div .... 0.1 s / div
calibrator 1 kHz, 3 V pk-pk
+5 V power supply
weight 0.19kg
overall dimensions 150x85x32 mm

AKTAKOM Oscilloscope Pro software (supplied with the device):

PURPOSE:

POSSIBILITIES:

Using the AULFConverter File Converter utility, you can convert a data file for reading by other AKTAKOM USB Lab applications in the same AKTAKOM USB Lab format, or convert the data into CSV text format, which can then be opened by any text editor or spreadsheet processor. It is possible to save to a file a ready-made image of the received signals on the graph in a file in BMP format or in vector formats WMF or EMF.

Measurement data printing is also supported, printing can be directed to a printer or to a graphic file.
An analysis module is built into the application for processing and automatic measurements.

THE STANDARD FUNCTIONS OF THE USB Oscillographic Analysis Module Includes:

digital filtering (polynomial, cumulative and spectral filters);
digital signal transformations (amplification / attenuation of the amplitude, compression / expansion of the time scale, vertical reflection, horizontal reverse, noise addition);
various mathematical functions of signals by channels (sum, difference, product, ratio, root mean square of channels, derivative, channel integral, channel product integral, channel correlation);
alarm that monitors the signal going beyond the set amplitude limits (available both in the recorder mode and in the oscilloscope mode);
functions of voltmeter, frequency meter, phase shift meter and integrator;
automatic measurement of pulse parameters (amplitude, peak-to-peak, overshoot, median, mean, standard deviation, frequency, period, pulse duration, duty cycle, rise time, fall time);
spectral analysis (selectable section of the oscillogram, determination of SOI, fundamental harmonic parameters, cursor measurements on the spectrogram, windows are supported: rectangular, triangular, Hann, Heming, Blackman, Blackman-Harris, Gauss, conic cosine, flat, exponential) and signal synthesis;
statistical processing of measurement results (for the selected parameter, the average, minimum, maximum, standard deviation are determined, a histogram of the probability distribution is built, the asymmetry and kurtosis of the distribution are determined, cursor measurements are made using the histogram);
formula calculator;
editor for emulating signals.

Standard complete set

USB oscilloscope
short instruction
AKTAKOM Oscilloscope Pro software for Windows XP / Vista / 7/8

The software in the standard delivery does not have physical media and can be downloaded in the "Software" section after purchasing and registering the device, indicating its serial number.

To download the software, click the Download button or go to the section "Technical support" -> "Downloadable files for your AKTAKOM device", then log in by entering your username and password. If you have not registered on the site www.aktakom.ru before, follow the link "Register" and provide all the necessary data.

In the standard delivery, the cost of the software is included in the price of the device. If the software is lost, there is an additional cost to download.